In the published European patent application EP 0347588 a description was given of a structural modification, in basic medium, of glycosaminoglycans with heparin and heparan structure with subsequent isolation from the reaction mixture of new derivatives with respect to the state of the art, as demonstrated unmistakably by the chemical and physical characteristics and especially by the .sup.13 C-NMR spectrum.
In the subsequent published European patent application EP 0380943 a further structural modification was described, in a basic or neutral medium, which, starting from the products formed in the reaction conditions described in EP 0347588, and from the glycosaminoglycans with heparin or heparan structure used as starting products in EP 0347588, originated a range of new products, different from those described in EP 0347588 and new with respect to the state of the art, as demonstrated unmistakably by the chemical and physical characteristics and especially by the .sup.13 C-NMR spectrum.
The chemical and physical characteristics of the products described in EP 0347588 and the results of a subsequent structural study described by Jaseia M., Rej R., Sauriol F., Perlin A. S. in Can. J. Chem 67, 1449-56 (1989), with the specific object of explaining the mechanism of the reaction of structural modification in a basic medium, have demonstrated that these derivatives show a modification which relates just one of the saccharide units characteristic of glycosaminoglycans with heparin or heparan structure, more specifically the unit of .alpha.-L-iduronic acid sulfated in position 2 and involving its transformation into a 2,3-epoxygulonic unit.
Likewise it has been demonstrated that semi-synthetic glycosaminoglycans with one 2,3-epoxygulonic unit and also glycosaminoglycans with heparin or heparan structure, under conditions of reaction similar to those described in EP 0380943, undergo a structural modification which also involves the saccharide unit of .alpha.-L-iduronic acid sulfated in position 2 and involving the transformation of this saccharide unit into a unit of non-sulfated .alpha.-L-iduronic acid or .alpha.-L-galacturonic acid, according to the conditions of reaction used.
So EP 0347588 describes semi-synthetic glycosaminoglycans containing an epoxy function between positions 2 and 3 of the unit of .alpha.-L-iduronic-2-O-sulfate acid taken as a starting point and the conditions of reaction necessary for obtaining them, while EP 0380943 describes products deriving from further transformation of the epoxide, confirmed as having one unit of non-sulfated .alpha.-L-iduronic or .alpha.-L-galacturonic acid, and the conditions of reaction necessary for obtaining them starting from the epoxyde itself or, as an alternative, starting from the glycosaminoglycans with heparin or heparan structure themselves, used as starting products in EP 0347588.